1. Field of the Invention
The present invention relates to an apparatus for evaporating ordinary temperature liquefied gases for stabilized supply, and more particularly relates to an evaporating apparatus designed to avoid accidents in which part of such liquefied gas is supplied in liquid form. In addition, the term "ordinary temperature liquefied gases" refers to liquefied petroleum gas (hereinafter abbreviated to LPG), chlorine gas, carbon dioxide gas and other gases which are liquefied at ordinary or low temperatures. Hereinafter, reference will be made to LPG taken up as representative.
2. Description of the Prior Art
LPG is utilized as fuel for homes, offices, firms, etc. The gas supplying system differs with the amount of gas to be used and with LPG composition, a simple example being one of which the gas phase in the vessel is extracted for supply and when the amount of gas to be used is large, a number of vessels are used to supply gas. If the amount of gas to be used is larger, a separately prepared vaporizer is used for forced vaporization by an electric heater or other heat source to supply gas. Thus, when the amount of gas to be used is relatively large as described, it has been necessary to prepare a number of vessels or use a large amount of electricity, which is not economical. However, it is unnecessary to secure any special heat source for vaporizing LPG since it is possible to make use of the atmosphere, sea water, river water, industrial water, underground water, hot waste water and other heat sources providing nearly natural heat, which are economical. These heat sources, however, are difficult with respect to manual control thereof. If, therefore, the temperature of the natural heat source abnormally lowers below a predicted value or the vaporizer becomes overloaded as by an abnormal increase in gas consumption, some of the LPG introduced into the vaporizer cannot vaporize and flows out of the vaporizer into the piping extending therefrom where it vaporizes under the influence of heat from the surroundings to exert a pressure abnormally higher than the planned pressure, or the liquid spouts at the terminal place of use.
Further, LPG is a mixture of propane, butane, etc., and butane (whose boiling point at atmospheric pressure is 0.degree. C.) is particularly difficult with respect to evaporation. Therefore, when the atmosphere or other heat source providing nearly natural heat is used, a problem occurs in that butane remains in the vaporizer or in the case of an evaporating chamber having a plurality of juxtaposed flow passages, such locally collects, interferring with uniform feeding of fresh LPG. As a result, part of the evaporating chamber loses its evaporating capacity, causing a decrease in the overall capacity or in the outlet temperature or sometimes even causing an accident in outflow of liquid.
As LPG is vaporized and consumed for a long period of time, a small amount of foreign matter, including heavy substances, contained in LPG accumulates in the evaporating chamber, which foreign matter must be periodically discharged. In the case of an evaporating apparatus of the type which requires a fixed amount of LPG to be stored at all times during evaporation, discharge of the drain including heavy substances entails outflow of a large amount of effective components, causing a large gas loss.